2,173 research outputs found
Hope, Ethnic Pride, and Academic Achievement: Positive Psychology and Latino Youth
Previous studies have found that hope has beneficial effects in athletics, academics, physical health, and mental well being in majority populations. Given the challenges Latino youth face in the United States, ethnic identity and hope may be a powerful buffer from these negative stressors. The current study aimed to identify whether chronic levels of hope related to academic performance, whether an ethnic pride manipulation altered state hope levels, and whether there was a link between ethnic identity and chronic hope among a sample of Latino youth. Results indicated that GPA and chronic hope levels were not related, a manipulation to boost ethic pride increased state hope, and that ethnic identity was related to chronic levels of hope. The findings suggest that ethnic identity is an important contributor to hope levels
Preliminary test results of the joint FAA-USAF-NASA runway research program. Part 1: Traction measurements of several runways under wet and dry conditions with a Boeing 727, a diagonal-braked vehicle, and a mu-meter
The stopping distance, brake application velocity, and time of brake application were measured for two modern jet transports, along with the NASA diagonal-braked vehicle and the British Mu-Meter on several runways, which when wetted, cover the range of slipperiness likely to be encountered in the United States. Tests were designed to determine if correlation between the aircraft and friction measuring vehicles exists. The test procedure, data reduction techniques, and preliminary test results obtained with the Boeing 727, the Douglas DC-9, and the ground vehicles are given. Time histories of the aircraft test run parameters are included
Elastic precursor of the transformation from glycolipid-nanotube to -vesicle
By the combination of optical tweezer manipulation and digital video
microscopy, the flexural rigidity of single glycolipid "nano" tubes has been
measured below the transition temperature at which the lipid tubules are
transformed into vesicles. Consequently, we have found a clear reduction of the
rigidity obviously before the transition as temperature increasing. Further
experiments of infrared spectroscopy (FT-IR) and differential scanning
calorimetry (DSC) have suggested a microscopic change of the tube walls,
synchronizing with the precursory softening of the nanotubes.Comment: 9 pages, 6 figure
Child Well-Being in Rich Countries: UNICEF’s Ranking Revisited, and New Symmetric Aggregating Operators Exemplified
In a report published in 2007 UNICEF measured six dimensions of child well-being for the majority of the economically advanced nations. No overall scores are given, but countries are listed in the order of their average rank on the dimensions, which are therefore implicitly assigned ‘equal importance’. In this study we take ‘equal importance’ to mean that the final aggregation is symmetrical in the scores and the ranks, i.e. permuting them leaves the aggregate unchanged. We rank the countries by aggregating the numerical information using a variety of techniques, geared to the measurement scales we distinguish (‘ordinal’, ‘interval’, ‘ratio’). The aggregators are symmetrical and mildly demanding, emphasizing good performance across the board. The rankings obtained deviate from the UNICEF ranking, but not over-dramatically. Our purpose is not only to study alternative approaches for the particular data at hand, but also to introduce and exemplify new and useful aggregation techniques: we propose ways to select weights for OWA-operators and weighted geometric means, and we suggest how to circumvent the choice of a power for the power means. In addition we extend the Borda method so that it values dominance as well
Testing the diffusion hypothesis as a mechanism of self-healing in Disperse orange 11 doped in PMMA
In this work, we show that reversible photodegradation of Disperse Orange 11
doped in PMMA is not due to dye diffusion - a common phenomenon observed in
many dye-doped polymers. The change in linear absorbance due to
photodegradation of the material shows an isobestic point, which is consistent
with the formation of a quasi-stable damaged species. Spatially-resolved
amplified spontaneous emission and fluorescence, both related to the population
density, are measured by scanning the pump beam over a burn mark. A numerical
model of the time evolution of the population density due to diffusion is
inconsistent with the experimental data suggesting that diffusion is not
responsible.Comment: 5 pages, 6 figure
Peroxidase-dependent metabolism of benzene's phenolic metabolites and its potential role in benzene toxicity and carcinogenicity.
The metabolism of two of benzene's phenolic metabolites, phenol and hydroquinone, by peroxidase enzymes has been studied in detail. Studies employing horseradish peroxidase and human myeloperoxidase have shown that in the presence of hydrogen peroxide phenol is converted to 4,4'-diphenoquinone and other covalent binding metabolites, whereas hydroquinone is converted solely to 1,4-benzoquinone. Surprisingly, phenol stimulates the latter conversion rather than inhibiting it, an effect that may play a role in the in vivo myelotoxicity of benzene. Indeed, repeated coadministration of phenol and hydroquinone to B6C3F1 mice results in a dramatic and significant decrease in bone marrow cellularity similar to that observed following benzene exposure. A mechanism of benzene-induced myelotoxicity is therefore proposed in which the accumulation and interaction of phenol and hydroquinone in the bone marrow and the peroxidase-dependent formation of 1,4-benzoquinone are important components. This mechanism may also be responsible, at least in part, for benzene's genotoxic effects, as 1,4-benzoquinone has been shown to damage DNA and is shown here to induce multiple micronuclei in human lymphocytes. Secondary activation of benzene's phenol metabolites in the bone marrow may therefore play an important role in benzene's myelotoxic and carcinogenic effects
Exploring the parameter space of MagLIF implosions using similarity scaling. I. Theoretical framework
Magneto-inertial fusion (MIF) concepts, such as the Magnetized Liner Inertial
Fusion (MagLIF) platform [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003
(2014)], constitute a promising path for achieving ignition and significant
fusion yields in the laboratory. The space of experimental input parameters
defining a MagLIF load is highly multi-dimensional, and the implosion itself is
a complex event involving many physical processes. In the first paper of this
series, we develop a simplified analytical model that identifies the main
physical processes at play during a MagLIF implosion. Using non-dimensional
analysis, we determine the most important dimensionless parameters
characterizing MagLIF implosions and provide estimates of such parameters using
typical fielded or experimentally observed quantities for MagLIF. We then show
that MagLIF loads can be "incompletely" similarity scaled, meaning that the
experimental input parameters of MagLIF can be varied such that many (but not
all) of the dimensionless quantities are conserved. Based on similarity-scaling
arguments, we can explore the parameter space of MagLIF loads and estimate the
performance of the scaled loads. In the follow-up papers of this series, we
test the similar scaling theory for MagLIF loads against simulations for two
different scaling "vectors", which include current scaling and rise-time
scaling.Comment: 24 pages, submitted to Physics of Plasma
Aerodynamic-structural analysis of dual bladed helicopter systems
The aerodynamic and structural feasibility of the birotor blade concept is assessed. The inviscid flow field about the dual bladed rotor was investigated to determine the aerodynamic characteristics for various dual rotor blade placement combinations with respect to blade stagger, gap, and angle of attack between the two blades. The boundary layer separation on the rotors was studied and three dimensional induced drag calculations for the dual rotor system are presented. The thrust and power requirements of the rotor system were predicted. NASTRAN, employed as the primary modeling tool, was used to obtain a model for predicting in plane bending, out of plane bending, and the torsional behavior of the birotors. Local hub loads, blade loads, and the natural frequencies for the birotor configuration are discussed
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